The size of many electronic components and modules, as well as the systems requiring these modules, continues to decrease. In parallel with the move toward miniaturization, the need for more efficient and more rapid module functionality continues to drive system requirements. In many instances, improved functionality results in increased thermal loading on electronic modules and their surrounding environment. For many applications, thermal loading degrades overall system speed and performance, and must be minimized. One approach to reducing system thermal loading is to design the module and its supporting structure in a manner so as to serve as a heat sink.
Cold-wall structures, to include what is often referred to as a “cold-wall egg crate structure”, are often used to house electronic modules. As the name implies, these structures have cooled walls or surfaces for conducting away the heat generated by the electronic modules. In particular, the standard cold-wall egg crate structure includes a plurality of compartments into which one or more electronic modules are inserted. The “front end” of each module, i.e. the end of the module inserted into the compartment, typically includes one or more connectors that blindly mate with connectors at the closed-end of the compartment.
To ensure adequate thermal conductivity between the electronic module and the cold-wall egg crate structure, the module housing must be in intimate contact with a cold-wall of the structure. More specifically, at least one surface of the module housing must be in contact with the cold-wall at a pressure adequate to optimize conductivity. For many applications, this pressure is at least 20 psi.
One current method for maintaining adequate contact pressure between the module housing and the cold-wall structure employs spring clips as a means for holding a module against its support. While spring clips work effectively to hold the module against a back wall, or the closed-end, of a cold-wall compartment, they are ineffective for holding the module against a top or bottom wall of the compartment. In order to ensure adequate heat transfer, the surface area of the module-to-cold-wall contact should be maximized. To achieve the maximum contact surface area, contact between the module and a top or a bottom wall of the compartment is required.
An approach for maintaining contact between a module and a top or bottom wall of a cold-wall structure is to permanently bond the module to the cold-wall. However, this approach has many limitations. In the confined compartments of a cold-wall egg crate structure, it is very difficult to ensure adequate adhesion of the module to the cold-wall. Similarly, it is difficult to ensure that the bonded module contacts the cold-wall at the desired pressure of greater than 20 psi. Moreover, permanent bonding effectively eliminates the possibility of exchanging modules within the compartment. For these reasons, bonding is often considered a less than desirable approach.
A further limitation of bonding is the inability to change the magnitude of the pressure at the module-to-cold-wall interface. Once the module is bonded in place, there is no opportunity to modify the pressure points or pressure values in order to change or maximize the heat transfer process.
Even in the absence of a thermal conductivity requirement, there is often a need to constrain or clamp modules within a small space having limited access. Soldering may be an option, however, access to the solder joints is often a problem. Additionally, soldered modules cannot be easily exchanged. Mechanical fasteners are yet another approach. These fasteners are often bulky, difficult to use, and expensive. Additionally, fasteners and clips often do not provide the flexibility needed to clamp a variety of modules of varying sizes. Moreover, each size of module typically requires a different size fastener.
Hence, there is a need for an apparatus to constrain or clamp modules within a structure that overcomes one or more of the drawbacks identified above.